Castor machine oil



Patented July 28, 1942 CASTOR MACHINE OIL Marcellus T. Flaxman, Wilmington, Calif., as-' signor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing.

Application July 19, 1938,

Serial No. 220,035

11 Claims.

The present invention relates to lubricating oils which have a stringy physical characteristic and which are commonly known as castor machine oils. Such oils are generally employed as lubricants in more or less open bearings or in loose bearings wherein excessive heat is not generated by friction. Castor machine oils are characterized by their stringinessj that is, the property of a drop of the oil, when placed between two surfaces being drawn apart, of making a string of extreme attenuation before breaking.

mineral oil, to be later blended readily with the base oil at distribution points. As a consequence, the blending of the complete product has been required at the point of original manufacture of such castor machine oils.

Furthermore, it has usually been found dimcult or even impossible to produce a castor machine oil in which the base oil possessed eastern characteristics, such characteristics being preferable to those of a castor machine oil with a western type base oil because of the greater stability to heat in use and the lower rate of change of viscosity with a rise in temperature.

It is therefore the main object of this invention to present to the industry a castor machine oil concentrate or additivematerial which can be readily blended with appropriate lubricating oils at any blending plant, thereby avoiding the necessity of preparing the final product at the point of manufacture and saving at least one shipping operation, namely that of the oil bulk. Another object of the invention is to produce castor machine oils and their concentrates or additive materials'which are not soluble in water and which are resistant to emulsification other objects may be attained by employing a blending agent in which both the mineral oil and the metallic soap, described hereinbelow,'are soluble. It has been further discovered that a castor machine oil concentrate which can be readily blended with lubricating oils to produce superior castor machine oils may be formed by commingling an aluminum soap of a higher fattyacid with a blending agent of the type of a polyhydroxy alcohol having one or more of the hydroxyl groups esterified by ricinoleic acid. It has been still further discovered that these blendin agents have a high solvent power for the aluminum soaps referred to hereinabove and that these blending agents possess the property of changing the metallic soap and mineral oil'mixture from the colloidal gel state to the colloidal sol condition at ordinary or slightly elevated temperatherewith. A still further object of the invention tures, thus making possible the production of castor machine oils which display the desired stringiness at atmospheric and somewhat elevated temperatures.

It has been still further discovered that a castor machine oil concentrate or additive material which can be subsequently readily dissolved in a suitable mineral oil to form a castor machine oil of the desired character, may be produced by commingling an aluminum soap of a higher fatty acid with a, polyhydroxyalcohol having one or more of the hydroxyl groups esterified by ricinoleic acid. This concentrate may be in a dry stateor may be produced in the form of a lubricating oil concentrate which contains relatively large proportions of the enumerated materials which are capable of imparting the desired stringiness to the final blend or product.

According to thepreferred form of the present invention, the mentioned fatty acid esters of polyhydroxy alcohols may be taken from a class consisting of glyceryl ricinoleates.

Therefore, broadly stated, the invention resides, in one of its aspects, in a castor machine oil concentrate or additive material capable of imparting the desired stringiness to the final blend with the base oil, this concentrate being either in a dry form or as a concentrated solution in a fraction of the oil. The invention further'resides in employing a polyhydroxy alcohol having one or more of the hydroxyl groups esterified by ricinoleic as a blending agent which may be compounded with a suitable soap, with or without. the addition of a quantity of oil, to form a concentrate which can be subsequently readily dissolved in an oil to form a superior castor ma- It has now been discovered that the above and chine oil. 1

Considering the invention in greater detail, the additive material is in the form of an aluminum soap and of an ester of a higher molecular weight polyhydric alcohol and a fatty acid, this an equivalent of aluminum stearate, it being understood that the characteristics of the final castor machine oil produced may be somewhat different depending on the type' of soap employed.

The term "aluminum stearate or aluminum stearate soap as used in this specification and hereinafter in the appended claims, refers to the aluminum soap or salt of stearic acid as it is produced commercially, that is aluminum distearate, which may contain small quantities of free stearic acid, aluminum monoand tristearates, and probably very small amounts of aluminum palmitates. Thus, the term is intended to include the ordinary commercial or technical grade of aluminum stearate. However, the term obviously also includes the chemically pure aluminum diand tri-stearates. The terms aluminum palmitate" and aluminum behenate similarly refer both to the commercial grades of the two soaps mentioned herein and to the aluminum soaps or salts of the chemically pure palmitic and behenic acids. The terms also include aluminum soaps or salts of the commercial grades of said acids, which latter may also contain certain quantities of stearic acid. The commercial grades of behenic acid may be obtained by the exhaustive hydrogenation of fish oils, followed by hydrolysis of the thus obtained glycerides,

g The invention also resides in an additive material comprising aluminum soap and a solubilizing agent of the type of the fatty acid esters of polyhydroxy alcohols mentioned hereinabove. This additive material may be in the form of about three parts of aluminum stearate and about onepart of the polyhydroxy alcohol having hydroxyl groups esterified by ricinoleic acid. It has been found, however, that the ratio of the aluminum soap to the above solubilizing or blending agent may vary within rather wide limits depending both on the metallic soap employed and the blending agent selected. Thus, the quantity of the soap may vary between about 70% and 90% of the additive material, or even higher, the remaining comprising the blending or solubilizing agent. mentioned hereinabove, relatively small amounts of which are required to produce the desired results. Depending upon the characteristics of the ingredients compounded to produce the resultant additive material or castor machine oil, and depending upon the fatty acid ester of the polyhydroxy alcohol selected, different quantities thereof shouldbe used. The invention, therefore, may further be stated to reside in an additive material, with or without the addition of a quantity of oil, this additive material containing between about 1% and 5% of a metallic soap of the type of aluminum stearate and between about 0.1% and 5% of a blending or solubilizing agent of the type of a polyhydroxy alcohol ester of a higher molecular weight fatty acid, said percentages being based on the final blend constituting the resulting superior castor machine oil.

In practicing the invention, the aluminum stearate, or an equivalent metal soap, and the solubilizing ester mentioned'hereinabove, may be introduced into the desired proportion of a mineral lubricating oil desired for the final prodnot, and the solution or dispersion of these materials may be eifected by agitation. This may be preferably accomplished also more readily by an elevation of the temperature, for example to approximately 320 F., or within a range of 200 F. to 400 F. The purpose of the heating is to cause dilution as well as for the purpose 'of dehydrating the mixture. It is to be realized that the removal of the small percentage of moisture which may be present is not essential. However, this dehydration is preferable at least in some cases.

If it is desired to produce a concentrate, the aluminum soap and the above solubilizing or blending agent may be dispersed as described above in only a small proportion of the mineral lubricating oil, for example in about 15% of lubricating oil based on the total oil-soap additive mixture. Again, the above solubilizing or blending agent may be intimately combined in a dry form with the aluminum stearate or a similar metal soap to yield a dry powder which may be subsequently added to the mineral lubricating oil in any desired proportion up to that required for the final blend. This blending of the concentrate or additive material with the base oil may thus be realized at the destination point. Inasmuch as the aluminum stearate or the like and the above enumerated fatty acid esters of poly- Zhydroxy alcohols are substantially anhydrous,

their admixture to form the dry powder may be conveniently effected. The quantities of the two substances may vary as described hereinabove, the relative percentages of these materials varying depending on the desired percentagesthereof in the final castor machine oil.

As an illustration of the invention, an additive material was prepared from aluminum stearate and glyceryl monoricinoleate as the blending or solubilizing agent. Instead of preparing a dry additive material, a concentrate containing some of the lubricating oil was produced. For this purpose, 56.7% by weight of aluminum stearate, 28.3% by weight of glyceryl monoricinoleate, and about 15% by weight of a lubricating oil having a viscosity of about 200 seconds Saybolt Universal at F. were used. To produce this concentrate the blending agent and the metal soap were first intimately commingled at room temperature. Thereafter, the oil was added and the mixture, while being agitated, was heated to about 310 F. and maintained at such temperature for approximately five minutes. The concentrate thus produced was readily miscible with the desired lubricating oil to produce a castor machine oil having excellent stringiness characteristics.

Although the above examples were'made in connection with the manufacture of castor machine oils containing lubricating oils having a viscosity of 200 seconds 'Saybolt Universal at 100 F., it is obvious that any appropriate lubricating oil may be employed. Thus, mineral lubricating oils of 40 to 70 S. A. E. grade may be used, but lighter or heavier oils are permissible.

Until the present time, it was practically essential to employ naphthenic base oils because of their higher solubility for aluminum stearate than paraffinic type oils.' It has been found, however, that the additive materials or concentrates constituting one of the objects of the present invention permit the use of eastern or paraffin base oils. This is highly desirable because of the relative stability of the parafiinic base oils and to their relative low rate of change of viscosity with temperature.

As an example of a castor machine oil prepared from a Pennsylvania stock oil according to the present invention, an additive material was produced by commingling aluminum stearate and glyceryl monoricinoleate in the proportions of between 3:1 and 4:1 to form a dry powder. The produced additive material was easily and readily soluble or miscible with Pennsylvania lubricating oils. Thus, a mixture formed by commingling 3% of the above described solid additive material with a Pennsylvania type lubricating oil having a viscosity of 158 seconds Saybolt Universal at 100 F., comprised a castor machine oil'having excellent characteristics of stringiness and at the same time displaying eastern characteristics as to stability and rate of change of viscosity with a change in temperature.

In employing the mentioned esters of polyhydric alcohols and high ricinoleic acid, the function of these is to impart to the aluminum stearate, or to asimilar metal soap, the characteristic of solubility or dispersibility of this soap in the lubricating oil employed in preparing the final blend. In other words, the ester appears to act as a common solvent. This function is not characteristic of all so-called common solvents or blending agents, but is characteristic of the types at present understood, and, to that extent, are to be considered as representative rather than as limiting, many variations being deemedto be within the scope of the appended claims.

I claim:

1. An addition agent for castor machine oils which comprises aluminum stearate and glyceryl monoricinoleate.

2. An agent according to claim 1 which is in dry solid form and free from oil.

3. A castor machine oil addition agent-comprising between about 70% and 90% of an aluminum soap of a higher fatty acid and between about 10% and 30% of glyceryl monoricinoleate.

4. An agent according to claim 3 which is free from oil.

of esters herein described and is quite necessary 5. A castor machine oil concentrate comprising a mineral lubricating oil, an aluminum soap of a higher fatty acid and an ester formed from ricinoleic acid and a polyhydric alcohol.

6. In composition of matter according to claim 5, wherein the ratio of the aluminum soap to the ester is between about 2 to 1 and 4 to 1, and wherein the mineral oil comprises a relatively small proportion of the total oil employed in the manufacture of the castor machine oil.

7. A mineral lubricating oil containing between about 1% and 5% of an aluminum soap of a higher fatty acid and between about 0.1% and 5% of an ester formed from a polyhydric alcohol and ricinoleic acid.

8. A castor machine oil which comprises a mineral lubricating oil, between about 1% and 5% of aluminum stearate and in the order of 0.1% and 5% of an ester formed from a polyhydric alcohol and ricinoleic acid.

9. In' a composition of matter according to claim 8 wherein the ester comprises glyceryl ricinoleate.

10. A castor machine oil according to claim 7 wherein the soap is an aluminum soap of a saturated higher fatty acid.

11. An oil according to claim '7 wherein the ester is a glyceryl ricinoleate.

MARCELLUS 'r. FLAXMAN. 

